US20090259077A1 - Process for the preparation of alkylene glycol - Google Patents
Process for the preparation of alkylene glycol Download PDFInfo
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- US20090259077A1 US20090259077A1 US12/420,564 US42056409A US2009259077A1 US 20090259077 A1 US20090259077 A1 US 20090259077A1 US 42056409 A US42056409 A US 42056409A US 2009259077 A1 US2009259077 A1 US 2009259077A1
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- catalyst
- hydrolysis catalyst
- hydrolysis
- carboxylation
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- LYCAIKOWRPUZTN-UHFFFAOYSA-N ethylene glycol Natural products OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 title claims abstract description 47
- -1 alkylene glycol Chemical compound 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 41
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- 239000003054 catalyst Substances 0.000 claims abstract description 233
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 167
- 230000007062 hydrolysis Effects 0.000 claims abstract description 165
- 238000006473 carboxylation reaction Methods 0.000 claims abstract description 77
- 230000021523 carboxylation Effects 0.000 claims abstract description 76
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 31
- 125000002947 alkylene group Chemical group 0.000 claims abstract description 23
- 230000000694 effects Effects 0.000 claims abstract description 23
- 230000015556 catabolic process Effects 0.000 claims abstract description 22
- 238000006731 degradation reaction Methods 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 17
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 238000012544 monitoring process Methods 0.000 claims description 8
- 238000002479 acid--base titration Methods 0.000 claims description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 25
- 239000002638 heterogeneous catalyst Substances 0.000 description 17
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 14
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 13
- 238000002474 experimental method Methods 0.000 description 13
- GKXDJYKZFZVASJ-UHFFFAOYSA-M tetrapropylazanium;iodide Chemical compound [I-].CCC[N+](CCC)(CCC)CCC GKXDJYKZFZVASJ-UHFFFAOYSA-M 0.000 description 11
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 9
- 238000004821 distillation Methods 0.000 description 8
- 239000002815 homogeneous catalyst Substances 0.000 description 8
- 235000011118 potassium hydroxide Nutrition 0.000 description 8
- 150000001450 anions Chemical class 0.000 description 7
- 230000007423 decrease Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 6
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 125000001453 quaternary ammonium group Chemical group 0.000 description 5
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical class OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 4
- MNZAKDODWSQONA-UHFFFAOYSA-N 1-dibutylphosphorylbutane Chemical compound CCCCP(=O)(CCCC)CCCC MNZAKDODWSQONA-UHFFFAOYSA-N 0.000 description 3
- HTWIZMNMTWYQRN-UHFFFAOYSA-N 2-methyl-1,3-dioxolane Chemical compound CC1OCCO1 HTWIZMNMTWYQRN-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 3
- 150000004679 hydroxides Chemical class 0.000 description 3
- 125000005496 phosphonium group Chemical group 0.000 description 3
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 3
- 229910000404 tripotassium phosphate Inorganic materials 0.000 description 3
- YFTHZRPMJXBUME-UHFFFAOYSA-N tripropylamine Chemical compound CCCN(CCC)CCC YFTHZRPMJXBUME-UHFFFAOYSA-N 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 150000003863 ammonium salts Chemical class 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 239000007857 degradation product Substances 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 230000003203 everyday effect Effects 0.000 description 2
- 150000002334 glycols Chemical class 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 239000003456 ion exchange resin Substances 0.000 description 2
- 229920003303 ion-exchange polymer Polymers 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- XYFCBTPGUUZFHI-UHFFFAOYSA-O phosphonium Chemical compound [PH4+] XYFCBTPGUUZFHI-UHFFFAOYSA-O 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 2
- 239000011736 potassium bicarbonate Substances 0.000 description 2
- 235000015497 potassium bicarbonate Nutrition 0.000 description 2
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 2
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 description 2
- 235000011181 potassium carbonates Nutrition 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 125000006273 (C1-C3) alkyl group Chemical group 0.000 description 1
- 238000001644 13C nuclear magnetic resonance spectroscopy Methods 0.000 description 1
- 238000004679 31P NMR spectroscopy Methods 0.000 description 1
- KFDVPJUYSDEJTH-UHFFFAOYSA-N 4-ethenylpyridine Chemical compound C=CC1=CC=NC=C1 KFDVPJUYSDEJTH-UHFFFAOYSA-N 0.000 description 1
- LRVWDNALCLWXDA-UHFFFAOYSA-N C.C.C.C.O.O.O=C=O.O=COO.OO Chemical compound C.C.C.C.O.O.O=C=O.O=COO.OO LRVWDNALCLWXDA-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910001508 alkali metal halide Inorganic materials 0.000 description 1
- 150000008045 alkali metal halides Chemical class 0.000 description 1
- 230000002528 anti-freeze Effects 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- CHQVQXZFZHACQQ-UHFFFAOYSA-M benzyl(triethyl)azanium;bromide Chemical compound [Br-].CC[N+](CC)(CC)CC1=CC=CC=C1 CHQVQXZFZHACQQ-UHFFFAOYSA-M 0.000 description 1
- USFRYJRPHFMVBZ-UHFFFAOYSA-M benzyl(triphenyl)phosphanium;chloride Chemical compound [Cl-].C=1C=CC=CC=1[P+](C=1C=CC=CC=1)(C=1C=CC=CC=1)CC1=CC=CC=C1 USFRYJRPHFMVBZ-UHFFFAOYSA-M 0.000 description 1
- 150000005323 carbonate salts Chemical class 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 150000007942 carboxylates Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000002354 daily effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 150000004862 dioxolanes Chemical class 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 1
- 150000004675 formic acid derivatives Chemical class 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000003278 mimic effect Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- LSMAIBOZUPTNBR-UHFFFAOYSA-N phosphanium;iodide Chemical compound [PH4+].[I-] LSMAIBOZUPTNBR-UHFFFAOYSA-N 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 235000011056 potassium acetate Nutrition 0.000 description 1
- WFIZEGIEIOHZCP-UHFFFAOYSA-M potassium formate Chemical compound [K+].[O-]C=O WFIZEGIEIOHZCP-UHFFFAOYSA-M 0.000 description 1
- 229910000160 potassium phosphate Inorganic materials 0.000 description 1
- 235000011009 potassium phosphates Nutrition 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 125000001424 substituent group Chemical group 0.000 description 1
- 125000000547 substituted alkyl group Chemical group 0.000 description 1
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 description 1
- RKHXQBLJXBGEKF-UHFFFAOYSA-M tetrabutylphosphanium;bromide Chemical compound [Br-].CCCC[P+](CCCC)(CCCC)CCCC RKHXQBLJXBGEKF-UHFFFAOYSA-M 0.000 description 1
- CCIYPTIBRAUPLQ-UHFFFAOYSA-M tetrabutylphosphanium;iodide Chemical compound [I-].CCCC[P+](CCCC)(CCCC)CCCC CCIYPTIBRAUPLQ-UHFFFAOYSA-M 0.000 description 1
- HWCKGOZZJDHMNC-UHFFFAOYSA-M tetraethylammonium bromide Chemical compound [Br-].CC[N+](CC)(CC)CC HWCKGOZZJDHMNC-UHFFFAOYSA-M 0.000 description 1
- DDFYFBUWEBINLX-UHFFFAOYSA-M tetramethylammonium bromide Chemical compound [Br-].C[N+](C)(C)C DDFYFBUWEBINLX-UHFFFAOYSA-M 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- DXJLCRNXYNRGRA-UHFFFAOYSA-M tributyl(methyl)azanium;iodide Chemical compound [I-].CCCC[N+](C)(CCCC)CCCC DXJLCRNXYNRGRA-UHFFFAOYSA-M 0.000 description 1
- XKFPGUWSSPXXMF-UHFFFAOYSA-N tributyl(methyl)phosphanium Chemical compound CCCC[P+](C)(CCCC)CCCC XKFPGUWSSPXXMF-UHFFFAOYSA-N 0.000 description 1
- RLZMYANQLOCZOB-UHFFFAOYSA-M tributyl(methyl)phosphanium;iodide Chemical compound [I-].CCCC[P+](C)(CCCC)CCCC RLZMYANQLOCZOB-UHFFFAOYSA-M 0.000 description 1
- XMQSELBBYSAURN-UHFFFAOYSA-M triphenyl(propyl)phosphanium;bromide Chemical compound [Br-].C=1C=CC=CC=1[P+](C=1C=CC=CC=1)(CCC)C1=CC=CC=C1 XMQSELBBYSAURN-UHFFFAOYSA-M 0.000 description 1
- IZYFBZDLXRHRLF-UHFFFAOYSA-N tritylphosphane;hydroiodide Chemical compound [I-].C=1C=CC=CC=1C(C=1C=CC=CC=1)([PH3+])C1=CC=CC=C1 IZYFBZDLXRHRLF-UHFFFAOYSA-N 0.000 description 1
- 230000003442 weekly effect Effects 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
- 150000003751 zinc Chemical class 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/095—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of organic acids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/03—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by addition of hydroxy groups to unsaturated carbon-to-carbon bonds, e.g. with the aid of H2O2
- C07C29/04—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by addition of hydroxy groups to unsaturated carbon-to-carbon bonds, e.g. with the aid of H2O2 by hydration of carbon-to-carbon double bonds
- C07C29/05—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by addition of hydroxy groups to unsaturated carbon-to-carbon bonds, e.g. with the aid of H2O2 by hydration of carbon-to-carbon double bonds with formation of absorption products in mineral acids and their hydrolysis
- C07C29/08—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by addition of hydroxy groups to unsaturated carbon-to-carbon bonds, e.g. with the aid of H2O2 by hydration of carbon-to-carbon double bonds with formation of absorption products in mineral acids and their hydrolysis the acid being phosphoric acid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
- C07C31/18—Polyhydroxylic acyclic alcohols
- C07C31/20—Dihydroxylic alcohols
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Definitions
- the present invention relates to a process for the preparation of an alkylene glycol from an alkylene oxide.
- Monoethylene glycol is used as a raw material in the manufacture of polyester fibres, polyethylene terephthalate (PET) bottles and resins. It is also incorporated into automobile antifreeze liquids.
- Monoethylene glycol may be prepared in a highly selective process from ethylene oxide via ethylene carbonate. This is typically carried out in a two-step process wherein the first step is the reaction of ethylene oxide with carbon dioxide to form ethylene carbonate, and the second step is the hydrolysis of ethylene carbonate to form ethylene glycol.
- Catalysts may be supplied to the carboxylation and hydrolysis steps to increase both the rate and selectivity of the reaction.
- WO 2007/144360 discloses a process for the manufacture of alkylene glycol from alkylene oxide via alkylene carbonate, wherein homogeneous carboxylation and hydrolysis catalysts are used.
- a homogeneous catalyst solution (comprising carboxylation catalyst and hydrolysis catalyst) is separated from crude monoethylene glycol and is recycled back to the carboxylation and hydrolysis reactors.
- the present inventors have sought to further improve the manufacture of alkylene glycol from alkylene oxide.
- the present invention provides a process for the preparation of an alkylene glycol from an alkylene oxide, wherein alkylene oxide reacts with carbon dioxide in the presence of a carboxylation catalyst to provide alkylene carbonate, wherein alkylene carbonate reacts with water in the presence of a hydrolysis catalyst to provide alkylene glycol, and wherein the active phase of the hydrolysis catalyst is one or more bases, comprising steps of
- the inventors have surprisingly discovered that during the process for the preparation of alkylene glycol, a basic hydrolysis catalyst degrades significantly more rapidly than the known carboxylation catalysts under typical conditions.
- the inventors have also discovered that as the amount of the basic hydrolysis catalyst decreases, there is an increased production of byproducts (e.g. aldehydes, dioxolanes), decreased conversion of alkylene carbonate and decreased selectivity (increased production of dialkylene glycol and higher glycols). Therefore the inventors have devised the process of the invention wherein the degradation and associated activity of the hydrolysis catalyst is monitored and additional hydrolysis catalyst is supplied to the process. By maintaining the amount of the hydrolysis catalyst above a minimum level, the process avoids increased production of byproducts and decreased selectivity.
- additional carboxylation catalyst is not required when the additional charges of hydrolysis catalyst are added.
- no additional carboxylation catalyst is added when an additional charge of hydrolysis catalyst is added.
- the benefits of the invention can still be achieved if small quantities of carboxylation catalyst are added with the additional hydrolysis catalyst, but a significant excess of hydrolysis catalyst should be added, i.e. the weight ratio of additional hydrolysis catalyst to additional carboxylation catalyst should be at least 5:1.
- FIG. 1 is a schematic diagram showing a process according to an embodiment of the invention.
- the present invention provides a process for the preparation of an alkylene glycol from an alkylene oxide, proceeding via an alkylene carbonate intermediate:
- R 1 , R 2 , R 3 and R 4 may independently be chosen from hydrogen or an optionally substituted alkyl group having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms.
- substituents moieties such as hydroxy groups may be present.
- R 1 , R 2 and R 3 represent hydrogen atoms and R 4 represents hydrogen or a non-substituted C 1 -C 3 -alkyl group and, more preferably, R 1 , R 2 , R 3 and R 4 all represent hydrogen atoms.
- alkylene oxides examples include ethylene oxide and propylene oxide.
- the most preferred alkylene oxide is ethylene oxide.
- Alkylene oxide reacts with carbon dioxide in the presence of a carboxylation catalyst to provide alkylene carbonate and alkylene carbonate reacts with water in the presence of a hydrolysis catalyst to provide alkylene glycol.
- a carboxylation catalyst to provide alkylene carbonate
- alkylene carbonate reacts with water in the presence of a hydrolysis catalyst to provide alkylene glycol.
- the reaction of alkylene oxide with carbon dioxide occurs predominantly in one or more carboxylation reactors, and the reaction of alkylene carbonate with water occurs predominantly in one or more hydrolysis reactors, wherein the one or more hydrolysis reactors are downstream of the one or more carboxylation reactors.
- the one or more hydrolysis reactors are downstream of the one or more carboxylation reactors.
- Preferably for every 10 moles of alkylene carbonate supplied to the one or more hydrolysis reactors at least 5 moles of alkylene glycol exits the one or more hydrolysis reactors.
- the reaction of alkylene oxide with carbon dioxide and the reaction of alkylene carbonate with water occurs predominantly in a single reactor.
- the carboxylation catalyst may be a heterogeneous or homogeneous catalyst.
- Homogeneous catalysts that are known to promote carboxylation include alkali metal halides such as potassium iodide and potassium bromide, and halogenated organic phosphonium or ammonium salts such as tributylmethylphosphonium iodide, tetrabutylphosphonium iodide, triphenylmethylphosphonium iodide, triphenyl-propylphosphonium bromide, triphenylbenzylphosphonium chloride, tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethylammonium bromide, tetrabutylammonium bromide and tributylmethylammonium iodide.
- Heterogeneous catalysts that promote carboxylation include quaternary ammonium and quaternary phosphonium halides immobilized on silica, quaternary ammonium and quaternary phosphonium halides bound to insoluble polystyrene beads, and metal salts such as zinc salts immobilised on solid supports containing quaternary ammonium or quaternary phosphonium groups, such as ion exchange resins containing quaternary ammonium or quaternary phosphonium groups.
- the carboxylation catalyst is a homogeneous catalyst, most preferably an organic phosphonium iodide or alkali halide salt.
- the active phase of the hydrolysis catalyst is one or more bases.
- the hydrolysis catalyst may be homogeneous or heterogeneous. Homogeneous catalysts that promote hydrolysis and that have a base as the active phase include hydroxides, bicarbonates, carbonates, carboxylates (e.g. acetates and formates) and phosphates. Examples include potassium hydroxide, sodium hydroxide, potassium bicarbonate, sodium bicarbonate, potassium carbonate, sodium carbonate, potassium acetate, potassium formate, tributylmethyl phosphonium hydroxide, potassium phosphate and disodium hydrogen phosphate.
- Heterogeneous catalysts that promote hydrolysis and that have a base as the active phase include hydroxide, bicarbonate and carbonate ions immobilised on solid supports, for example hydroxide, bicarbonate or carbonate immobilised on ion exchange resins containing quaternary ammonium or quaternary phosphonium groups; basic alumina; basic zeolite; and poly-4-vinyl-pyridine.
- the hydrolysis catalyst has bicarbonate anions as the active phase.
- Metal carbonates, hydroxides and bicarbonates such as potassium carbonate, potassium hydroxide and potassium bicarbonate, all provide bicarbonate anions as the active phase.
- Carbon dioxide is present during the hydrolysis reaction (it is a product of the hydrolysis reaction), and in the presence of carbon dioxide, hydroxides, carbonates and bicarbonates react as shown:
- hydroxide and carbonate salts can act as a source of bicarbonate anions.
- the initial charge of the carboxylation catalyst and the initial charge of the hydrolysis catalyst catalyse the reaction of alkylene oxide with carbon dioxide, and catalyse the reaction of alkylene carbonate with water.
- the process preferably uses a catalyst recycle loop whereby catalyst is separated from the alkylene glycol product and is recycled so that it is combined with the alkylene oxide reactant.
- An initial charge of homogeneous catalyst is preferably added by supplying a solution of the catalyst to the catalyst recycle loop such that the catalyst is combined with the alkylene oxide reactant. If both the carboxylation catalyst and the hydrolysis catalyst are homogeneous, then the catalysts are preferably supplied to the catalyst recycle loop as a solution comprising both of the catalysts.
- heterogeneous carboxylation or heterogeneous hydrolysis catalysts are contained within two or more separate vessels arranged in parallel and wherein said vessels have associated switching means such that in operation the feed can be switched between the vessels.
- the degradation and associated activity of the hydrolysis catalyst is monitored.
- the degradation can be measured by taking samples, preferably from a recycle loop, and measuring the concentration of basic hydrolysis catalyst by acid/base titration. From the concentration of hydrolysis catalyst in the recycle loop it is possible to calculate the concentration of hydrolysis catalyst in the reactor, and the activity of the catalyst will be proportional to the concentration of hydrolysis catalyst in the reactor.
- the absolute concentration of the hydrolysis catalyst it is also possible to monitor degradation by measuring the change in ratio of hydrolysis catalyst to carboxylation catalyst, again by taking samples from a recycle loop and carrying out acid/base titration. The relative amount of hydrolysis catalyst will decrease as the hydrolysis catalyst degrades, and the associated activity of the hydrolysis catalyst will also decrease.
- the degradation can be measured by taking a sample of the heterogeneous catalyst, measuring the concentration of basic anions by titration and comparing this with the concentration of basic anions in a sample of fresh catalyst.
- the degradation can be measured by switching reactor vessels packed with heterogeneous catalyst, regenerating the heterogeneous catalyst by passing a solution comprising basic anions through the catalyst bed, and measuring the quantity of basic anions removed from the solution during the regeneration.
- the degradation can be measured by switching reactor vessels packed with heterogeneous catalyst and monitoring the relative activity of fresh and used beds (activity can be assessed by taking samples of the product stream and analysing the samples using standard techniques).
- Monitoring of the degradation of the hydrolysis catalyst is preferably carried out at least once every week and more preferably is carried out every day.
- the hydrolysis catalyst When the activity of the hydrolysis catalyst has fallen below a minimum level, an additional charge of the hydrolysis catalyst is added.
- a preferred way of assessing whether the activity of the hydrolysis catalyst has fallen below a minimum level is to set a minimum concentration of hydrolysis catalyst that must be present in the recycle stream.
- a preferred way of assessing whether the activity of the hydrolysis catalyst has fallen below a minimum level is to set a minimum conversion that must be achieved by a reactor vessel containing hydrolysis catalyst.
- an additional charge of the hydrolysis catalyst is added. If an additional charge of carboxylation catalyst is added when the additional charge of the hydrolysis catalyst is added, the weight ratio of additional hydrolysis catalyst to additional carboxylation catalyst is at least 5:1, preferably at least 10:1, more preferably at least 50:1. Most preferably, the addition charge of the hydrolysis catalyst is added without adding any additional carboxylation catalyst. If the hydrolysis catalyst is homogeneous, the additional charge of catalyst is preferably added by supplying a solution of the hydrolysis catalyst to the catalyst recycle loop. The additional charge does not have to be the same catalyst compound as the initial charge.
- the initial charge can be a potassium carbonate solution and the additional charge(s) can be potassium hydroxide solution.
- the additional charge of catalyst is preferably added by replacing the used heterogeneous catalyst with fresh heterogeneous catalyst.
- a simple way to achieve this is to have heterogeneous hydrolysis catalysts contained within two or more separate vessels arranged in parallel, wherein said vessels have associated switching means such that in operation the feed can be switched between the vessels.
- the heterogeneous catalyst can be replaced with fresh heterogeneous catalyst by switching the feed to a vessel containing fresh catalyst.
- Degraded heterogeneous catalyst wherein the heterogeneous comprises basic anions on a support can be regenerated by treatment with a solution of basic anions.
- the hydrolysis catalyst is a homogeneous catalyst, there is likely to be a desirable upper limit on the concentration of the hydrolysis catalyst.
- the inventors have discovered that as the concentration of hydrolysis catalyst increases, the degradation of carboxylation catalysts such as halogenated organic phosphonium or ammonium salts, can also increase. Therefore, when an additional charge of the hydrolysis catalyst is added, the amount of additional catalyst is preferably such that the total concentration of hydrolysis catalyst will not be above an upper limit. This limit can be determined by observing how the carboxylation degrades as the hydrolysis catalyst concentration increases.
- steps (b) and (c) are preferably operated continually, e.g. monitoring of the hydrolysis catalyst is daily or weekly, and addition of additional hydrolysis catalyst occurs as necessary. However, after a period of monitoring and addition of hydrolysis catalyst, e.g. after several weeks or months of monitoring and several additional charges of hydrolysis catalyst, it may then be preferable to add additional charges of both carboxylation catalyst and hydrolysis catalyst. For example, step (c) may be carried out three or more times before additional charges of hydrolysis catalyst and carboxylation catalyst are added.
- FIG. 1 shows a preferred embodiment of the process of the invention.
- the apparatus includes a carboxylation reactor ( 1 ), a hydrolysis reactor ( 5 ) and a distillation column ( 7 ).
- Carbon dioxide ( 2 ) is fed to the carboxylation reactor.
- Ethylene oxide and water ( 3 ) are also fed to the carboxylation reactor.
- An initial charge of homogeneous carboxylation catalyst and an initial charge of homogeneous hydrolysis catalyst are fed ( 10 ) to a line that feeds into the ethylene oxide and water feed line ( 3 ). This catalyses the carboxylation reaction.
- a reaction stream comprising ethylene carbonate produced in the carboxylation reactor ( 1 ), and also comprising carboxylation catalyst and hydrolysis catalyst is fed ( 4 ) to the hydrolysis reactor ( 5 ).
- the hydrolysis catalyst catalyses the reaction of ethylene carbonate to ethylene glycol in the hydrolysis reactor ( 5 ).
- the product stream from the hydrolysis reactor ( 5 ) is fed ( 6 ) to a distillation column ( 7 ).
- Glycol products ( 8 ) are extracted from the distillation column ( 7 ) and a catalyst solution of carboxylation catalyst and hydrolysis catalyst is fed ( 9 ) back to the ethylene oxide and water feed line ( 3 ).
- the concentration of the hydrolysis catalyst is measured every day by taking samples from the recycle loop ( 9 ). Acid/base titration of the samples provides a measurement of the concentration of the hydrolysis catalyst. When the concentration of hydrolysis catalyst falls below a minimum level, an additional charge of the homogeneous hydrolysis catalyst is added at point ( 10 ) (and no further carboxylation catalyst is added).
- Table 1 shows the conditions for experiments 1a-1c:
- the amount of additional catalyst is preferably such that the total concentration of hydrolysis catalyst will not be above an upper limit. This avoids the degradation of carboxylation catalyst illustrated by this experiment.
- the amount of additional catalyst is preferably such that the total concentration of hydrolysis catalyst will not be above an upper limit. This avoids the degradation of carboxylation catalyst illustrated by this experiment.
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Abstract
Description
- The present invention relates to a process for the preparation of an alkylene glycol from an alkylene oxide.
- Monoethylene glycol is used as a raw material in the manufacture of polyester fibres, polyethylene terephthalate (PET) bottles and resins. It is also incorporated into automobile antifreeze liquids.
- Monoethylene glycol may be prepared in a highly selective process from ethylene oxide via ethylene carbonate. This is typically carried out in a two-step process wherein the first step is the reaction of ethylene oxide with carbon dioxide to form ethylene carbonate, and the second step is the hydrolysis of ethylene carbonate to form ethylene glycol.
- Catalysts may be supplied to the carboxylation and hydrolysis steps to increase both the rate and selectivity of the reaction. WO 2007/144360 discloses a process for the manufacture of alkylene glycol from alkylene oxide via alkylene carbonate, wherein homogeneous carboxylation and hydrolysis catalysts are used. A homogeneous catalyst solution (comprising carboxylation catalyst and hydrolysis catalyst) is separated from crude monoethylene glycol and is recycled back to the carboxylation and hydrolysis reactors.
- The present inventors have sought to further improve the manufacture of alkylene glycol from alkylene oxide.
- The present invention provides a process for the preparation of an alkylene glycol from an alkylene oxide, wherein alkylene oxide reacts with carbon dioxide in the presence of a carboxylation catalyst to provide alkylene carbonate, wherein alkylene carbonate reacts with water in the presence of a hydrolysis catalyst to provide alkylene glycol, and wherein the active phase of the hydrolysis catalyst is one or more bases, comprising steps of
- (a) adding an initial charge of the carboxylation catalyst and an initial charge of the hydrolysis catalyst to catalyse the reaction of alkylene oxide with carbon dioxide, and to catalyse the reaction of alkylene carbonate with water;
- (b) monitoring the degradation and activity of the hydrolysis catalyst; and
- (c) when the activity of the hydrolysis catalyst has fallen below a minimum level, adding an additional charge of the hydrolysis catalyst, wherein if an additional charge of carboxylation catalyst is added when the additional charge of the hydrolysis catalyst is added, the weight ratio of additional hydrolysis catalyst to additional carboxylation catalyst is at least 5:1.
- The inventors have surprisingly discovered that during the process for the preparation of alkylene glycol, a basic hydrolysis catalyst degrades significantly more rapidly than the known carboxylation catalysts under typical conditions. The inventors have also discovered that as the amount of the basic hydrolysis catalyst decreases, there is an increased production of byproducts (e.g. aldehydes, dioxolanes), decreased conversion of alkylene carbonate and decreased selectivity (increased production of dialkylene glycol and higher glycols). Therefore the inventors have devised the process of the invention wherein the degradation and associated activity of the hydrolysis catalyst is monitored and additional hydrolysis catalyst is supplied to the process. By maintaining the amount of the hydrolysis catalyst above a minimum level, the process avoids increased production of byproducts and decreased selectivity. Because the carboxylation catalyst typically degrades much more slowly than the hydrolysis catalyst, additional carboxylation catalyst is not required when the additional charges of hydrolysis catalyst are added. Preferably no additional carboxylation catalyst is added when an additional charge of hydrolysis catalyst is added. (The benefits of the invention can still be achieved if small quantities of carboxylation catalyst are added with the additional hydrolysis catalyst, but a significant excess of hydrolysis catalyst should be added, i.e. the weight ratio of additional hydrolysis catalyst to additional carboxylation catalyst should be at least 5:1.)
-
FIG. 1 is a schematic diagram showing a process according to an embodiment of the invention. - The present invention provides a process for the preparation of an alkylene glycol from an alkylene oxide, proceeding via an alkylene carbonate intermediate:
- Suitably, R1, R2, R3 and R4 may independently be chosen from hydrogen or an optionally substituted alkyl group having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms. As substituents, moieties such as hydroxy groups may be present. Preferably, R1, R2 and R3 represent hydrogen atoms and R4 represents hydrogen or a non-substituted C1-C3-alkyl group and, more preferably, R1, R2, R3 and R4 all represent hydrogen atoms.
- Examples of suitable alkylene oxides therefore include ethylene oxide and propylene oxide. In the present invention the most preferred alkylene oxide is ethylene oxide.
- Alkylene oxide reacts with carbon dioxide in the presence of a carboxylation catalyst to provide alkylene carbonate and alkylene carbonate reacts with water in the presence of a hydrolysis catalyst to provide alkylene glycol. Processes for preparing ethylene glycol by this route are described in detail in U.S. Pat. No. 6,080,897, U.S. Pat. No. 6,187,972 and WO 2009/021830, which are all herein incorporated by reference in their entirety. In one embodiment of the invention, the reaction of alkylene oxide with carbon dioxide occurs predominantly in one or more carboxylation reactors, and the reaction of alkylene carbonate with water occurs predominantly in one or more hydrolysis reactors, wherein the one or more hydrolysis reactors are downstream of the one or more carboxylation reactors. Preferably for every 10 moles of alkylene oxide supplied to the one or more carboxylation reactors, at least 5 moles of alkylene carbonate exits the one or more carboxylation reactors. Preferably for every 10 moles of alkylene carbonate supplied to the one or more hydrolysis reactors, at least 5 moles of alkylene glycol exits the one or more hydrolysis reactors. In an alternative embodiment of the invention, the reaction of alkylene oxide with carbon dioxide and the reaction of alkylene carbonate with water occurs predominantly in a single reactor. Preferably for every 10 moles of alkylene oxide supplied to the reactor, less than 2 moles of alkylene carbonate and greater than 6 moles of alkylene glycol exits the reactor.
- The carboxylation catalyst may be a heterogeneous or homogeneous catalyst. Homogeneous catalysts that are known to promote carboxylation include alkali metal halides such as potassium iodide and potassium bromide, and halogenated organic phosphonium or ammonium salts such as tributylmethylphosphonium iodide, tetrabutylphosphonium iodide, triphenylmethylphosphonium iodide, triphenyl-propylphosphonium bromide, triphenylbenzylphosphonium chloride, tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethylammonium bromide, tetrabutylammonium bromide and tributylmethylammonium iodide. Heterogeneous catalysts that promote carboxylation include quaternary ammonium and quaternary phosphonium halides immobilized on silica, quaternary ammonium and quaternary phosphonium halides bound to insoluble polystyrene beads, and metal salts such as zinc salts immobilised on solid supports containing quaternary ammonium or quaternary phosphonium groups, such as ion exchange resins containing quaternary ammonium or quaternary phosphonium groups. Preferably the carboxylation catalyst is a homogeneous catalyst, most preferably an organic phosphonium iodide or alkali halide salt.
- The active phase of the hydrolysis catalyst is one or more bases. The hydrolysis catalyst may be homogeneous or heterogeneous. Homogeneous catalysts that promote hydrolysis and that have a base as the active phase include hydroxides, bicarbonates, carbonates, carboxylates (e.g. acetates and formates) and phosphates. Examples include potassium hydroxide, sodium hydroxide, potassium bicarbonate, sodium bicarbonate, potassium carbonate, sodium carbonate, potassium acetate, potassium formate, tributylmethyl phosphonium hydroxide, potassium phosphate and disodium hydrogen phosphate. Heterogeneous catalysts that promote hydrolysis and that have a base as the active phase include hydroxide, bicarbonate and carbonate ions immobilised on solid supports, for example hydroxide, bicarbonate or carbonate immobilised on ion exchange resins containing quaternary ammonium or quaternary phosphonium groups; basic alumina; basic zeolite; and poly-4-vinyl-pyridine.
- In a preferred embodiment the hydrolysis catalyst has bicarbonate anions as the active phase. Metal carbonates, hydroxides and bicarbonates, such as potassium carbonate, potassium hydroxide and potassium bicarbonate, all provide bicarbonate anions as the active phase. Carbon dioxide is present during the hydrolysis reaction (it is a product of the hydrolysis reaction), and in the presence of carbon dioxide, hydroxides, carbonates and bicarbonates react as shown:
- Therefore, hydroxide and carbonate salts can act as a source of bicarbonate anions.
- The initial charge of the carboxylation catalyst and the initial charge of the hydrolysis catalyst catalyse the reaction of alkylene oxide with carbon dioxide, and catalyse the reaction of alkylene carbonate with water. If one or both of the catalysts are homogeneous, the process preferably uses a catalyst recycle loop whereby catalyst is separated from the alkylene glycol product and is recycled so that it is combined with the alkylene oxide reactant. An initial charge of homogeneous catalyst is preferably added by supplying a solution of the catalyst to the catalyst recycle loop such that the catalyst is combined with the alkylene oxide reactant. If both the carboxylation catalyst and the hydrolysis catalyst are homogeneous, then the catalysts are preferably supplied to the catalyst recycle loop as a solution comprising both of the catalysts. An initial charge of heterogeneous catalyst is added by packing the heterogeneous catalyst into a reactor where the carboxylation and/or the hydrolysis will occur. In one embodiment of the invention, heterogeneous carboxylation or heterogeneous hydrolysis catalysts are contained within two or more separate vessels arranged in parallel and wherein said vessels have associated switching means such that in operation the feed can be switched between the vessels.
- The degradation and associated activity of the hydrolysis catalyst is monitored. For a homogeneous hydrolysis catalyst the degradation can be measured by taking samples, preferably from a recycle loop, and measuring the concentration of basic hydrolysis catalyst by acid/base titration. From the concentration of hydrolysis catalyst in the recycle loop it is possible to calculate the concentration of hydrolysis catalyst in the reactor, and the activity of the catalyst will be proportional to the concentration of hydrolysis catalyst in the reactor. Instead of determining the absolute concentration of the hydrolysis catalyst, it is also possible to monitor degradation by measuring the change in ratio of hydrolysis catalyst to carboxylation catalyst, again by taking samples from a recycle loop and carrying out acid/base titration. The relative amount of hydrolysis catalyst will decrease as the hydrolysis catalyst degrades, and the associated activity of the hydrolysis catalyst will also decrease. For a heterogeneous catalyst wherein the active species are basic anions, the degradation can be measured by taking a sample of the heterogeneous catalyst, measuring the concentration of basic anions by titration and comparing this with the concentration of basic anions in a sample of fresh catalyst. Alternatively, the degradation can be measured by switching reactor vessels packed with heterogeneous catalyst, regenerating the heterogeneous catalyst by passing a solution comprising basic anions through the catalyst bed, and measuring the quantity of basic anions removed from the solution during the regeneration. For other types of heterogeneous catalyst, e.g. basic alumina, the degradation can be measured by switching reactor vessels packed with heterogeneous catalyst and monitoring the relative activity of fresh and used beds (activity can be assessed by taking samples of the product stream and analysing the samples using standard techniques).
- Monitoring of the degradation of the hydrolysis catalyst is preferably carried out at least once every week and more preferably is carried out every day.
- When the activity of the hydrolysis catalyst has fallen below a minimum level, an additional charge of the hydrolysis catalyst is added. When the hydrolysis catalyst is a homogeneous catalyst, a preferred way of assessing whether the activity of the hydrolysis catalyst has fallen below a minimum level is to set a minimum concentration of hydrolysis catalyst that must be present in the recycle stream. When the hydrolysis catalyst is a heterogeneous catalyst, a preferred way of assessing whether the activity of the hydrolysis catalyst has fallen below a minimum level is to set a minimum conversion that must be achieved by a reactor vessel containing hydrolysis catalyst.
- When the activity of hydrolysis catalyst has fallen below the minimum level, an additional charge of the hydrolysis catalyst is added. If an additional charge of carboxylation catalyst is added when the additional charge of the hydrolysis catalyst is added, the weight ratio of additional hydrolysis catalyst to additional carboxylation catalyst is at least 5:1, preferably at least 10:1, more preferably at least 50:1. Most preferably, the addition charge of the hydrolysis catalyst is added without adding any additional carboxylation catalyst. If the hydrolysis catalyst is homogeneous, the additional charge of catalyst is preferably added by supplying a solution of the hydrolysis catalyst to the catalyst recycle loop. The additional charge does not have to be the same catalyst compound as the initial charge. For example, the initial charge can be a potassium carbonate solution and the additional charge(s) can be potassium hydroxide solution. If the hydrolysis catalyst is heterogeneous, the additional charge of catalyst is preferably added by replacing the used heterogeneous catalyst with fresh heterogeneous catalyst. A simple way to achieve this is to have heterogeneous hydrolysis catalysts contained within two or more separate vessels arranged in parallel, wherein said vessels have associated switching means such that in operation the feed can be switched between the vessels. The heterogeneous catalyst can be replaced with fresh heterogeneous catalyst by switching the feed to a vessel containing fresh catalyst. Degraded heterogeneous catalyst wherein the heterogeneous comprises basic anions on a support can be regenerated by treatment with a solution of basic anions.
- When the hydrolysis catalyst is a homogeneous catalyst, there is likely to be a desirable upper limit on the concentration of the hydrolysis catalyst. The inventors have discovered that as the concentration of hydrolysis catalyst increases, the degradation of carboxylation catalysts such as halogenated organic phosphonium or ammonium salts, can also increase. Therefore, when an additional charge of the hydrolysis catalyst is added, the amount of additional catalyst is preferably such that the total concentration of hydrolysis catalyst will not be above an upper limit. This limit can be determined by observing how the carboxylation degrades as the hydrolysis catalyst concentration increases.
- In a conventional process it would be usual to replenish both the carboxylation catalyst and the hydrolysis catalyst at regular intervals. The present invention differs in that it has been recognised that it is beneficial to provide additional hydrolysis catalyst when not providing additional carboxylation catalyst (or at least by providing a significant excess of hydrolysis catalyst to carboxylation catalyst). In the present invention steps (b) and (c) are preferably operated continually, e.g. monitoring of the hydrolysis catalyst is daily or weekly, and addition of additional hydrolysis catalyst occurs as necessary. However, after a period of monitoring and addition of hydrolysis catalyst, e.g. after several weeks or months of monitoring and several additional charges of hydrolysis catalyst, it may then be preferable to add additional charges of both carboxylation catalyst and hydrolysis catalyst. For example, step (c) may be carried out three or more times before additional charges of hydrolysis catalyst and carboxylation catalyst are added.
-
FIG. 1 shows a preferred embodiment of the process of the invention. The apparatus includes a carboxylation reactor (1), a hydrolysis reactor (5) and a distillation column (7). Carbon dioxide (2) is fed to the carboxylation reactor. Ethylene oxide and water (3) are also fed to the carboxylation reactor. An initial charge of homogeneous carboxylation catalyst and an initial charge of homogeneous hydrolysis catalyst are fed (10) to a line that feeds into the ethylene oxide and water feed line (3). This catalyses the carboxylation reaction. A reaction stream comprising ethylene carbonate produced in the carboxylation reactor (1), and also comprising carboxylation catalyst and hydrolysis catalyst is fed (4) to the hydrolysis reactor (5). The hydrolysis catalyst catalyses the reaction of ethylene carbonate to ethylene glycol in the hydrolysis reactor (5). The product stream from the hydrolysis reactor (5) is fed (6) to a distillation column (7). Glycol products (8) are extracted from the distillation column (7) and a catalyst solution of carboxylation catalyst and hydrolysis catalyst is fed (9) back to the ethylene oxide and water feed line (3). The concentration of the hydrolysis catalyst is measured every day by taking samples from the recycle loop (9). Acid/base titration of the samples provides a measurement of the concentration of the hydrolysis catalyst. When the concentration of hydrolysis catalyst falls below a minimum level, an additional charge of the homogeneous hydrolysis catalyst is added at point (10) (and no further carboxylation catalyst is added). - The following examples are illustrative but not limiting of the invention.
- Effect of Hydrolysis Catalyst concentration
- A number experiments were performed with different amounts of hydrolysis catalyst in order to illustrate the invention. Lower amounts of hydrolysis catalyst illustrate the circumstance where degradation of the hydrolysis catalyst has occurred. Higher amounts of hydrolysis catalyst illustrate the circumstance where additional hydrolysis catalyst has been added such that the concentration of hydrolysis catalyst is above a preferred limit.
- The experiments are described making use of the process outline of
FIG. 1 . Batch autoclave experiments were performed in order to mimic process conditions {temperature, pressure, catalyst composition, etc) in process apparatus (the hydrolysis reactor (5) and distillation column (7)) with contents representing the various process streams. In general the various process streams in the process apparatus and in the process lines contain the following components: - Carboxylation reactor (1): ethylene oxide/ethylene carbonate/water/carboxylation catalyst/hydrolysis catalyst/CO2
- Line (4): ethylene carbonate/water/carboxylation catalyst/hydrolysis catalyst/CO2
- Hydrolysis reactor (5): ethylene carbonate/monoethylene glycol/water/carboxylation catalyst/hydrolysis catalyst/CO2
- Line (6): monoethylene glycol/water/carboxylation catalyst/hydrolysis catalyst
- Distillation column (7): monoethylene glycol/water/carboxylation catalyst/hydrolysis catalyst
- In carboxylation reactor (1), ethylene oxide is converted into ethylene carbonate under the influence of the carboxylation catalyst.
- In hydrolysis reactor (5), ethylene carbonate is converted into monoethylene glycol under the influence of the hydrolysis catalyst.
- In distillation column (7) glycols (mainly monoethylene glycol, some diethylene glycol) and water are separated from both catalysts(a 20-70% wt solution in monoethylene glycol/diethylene glcyol).
- In this experiment the effect of the amount of a commonly used basic hydrolysis catalyst (K3PO4) in the presence of a commonly used carboxylation catalyst (KI) on by-product formation (e.g. formation of 2-methyl-1,3-dioxolane) and selectivity to monoethylene glycol (assessed by the formation of a higher glycol diethylene glycol) is evaluated under conditions representative for hydrolysis reactor (5) and with a composition representative for the process stream of line (4) and the contents of reactor (5).
- Table 1 shows the conditions for experiments 1a-1c:
-
TABLE 1 Exp 1a Exp 1b Exp 1c Water (g) 20 20 20 Monoethylene glycol (g) 20 20 20 Ethylene carbonate (g) 40 40 40 KI (g) 3.9 3.9 3.9 KI (mol/l) 0.30 0.30 0.30 K3PO4 (g) 0.04 0.09 0.42 K3PO4 (mol/l) 0.003 0.005 0.025 Temperature (° C.) 150 150 150 CO2 pressure (barg) 20 20 20 Time (h) 4 and 6 4 4 - After 4 h (and for experiment 1a also after 6 h, because of the slower ethylene carbonate hydrolysis) the resulting mixtures were analyzed by GC analysis. The results are shown in Table 2:
-
TABLE 2 Exp Exp Exp Exp 1a 1a 1b 1c Component @ 4 h @ 6 h @ 4 h @ 4 h Ethylene carbonate (% wt) 0.41 0.04 0.07 0.007 Monoethylene glycol (% wt) 75.9 76.3 76.4 75.7 Diethylene glycol (% wt) 0.73 0.78 0.48 0.18 Diethylene glycol (ppm) 7341 7774 4831 1821 2-methyl-1,3-dioxolane 298 310 173 33 (ppm) - These results clearly demonstrates that low hydrolysis catalyst concentration (which could result from degradation of the hydrolysis catalyst and failure to add additional hydrolysis catalyst) results not only in slow hydrolysis of ethylene carbonate, but also in more undesired by-product formation (e.g. 2-methyl-1,3-dioxolane) and in worse monoethylene glycol selectivity (100%*MEG/(MEG+DEG)). In the present invention, the activity of the hydrolysis catalyst is monitored and further hydrolysis catalyst is added when the activity falls below a specified level. This avoids the slow hydrolysis, high by-product formation and poor selectivity illustrated by this experiment.
- In this experiment the effect of the amount of a commonly used basic hydrolysis catalyst 2 (KOH) on the stability of a commonly used carboxylation catalyst, tetra-n-propylammoniumiodide (TPAI) is evaluated under conditions representative for distillation column (7) and with a composition representative for the process stream in line (6) and the contents of column (7).
- Table 3 shows the conditions for experiments 2a-2c:
-
TABLE 3 Exp 2a Exp 2b Exp 2c Water (g) 11 11 11 Monoethylene glycol (g) 47 47 47 TPAI (g) 2.3 2.3 2.3 TPAI (mol/l) 0.12 0.12 0.12 KOH (g) 0.02 0.34 1.74 KOH (mol/l) 0.006 0.10 0.49 Temperature (° C.) 160 160 160 N2 pressure (barg) 20 20 20 Time (h) 22 22 22 - After 22 h the resulting mixture was analyzed by 13C NMR; TPAI catalyst degradation is visible by a decline in TPAI content and the formation of TPA (tri-n-propylamine), which is a TPAI degradation product. The results are shown in Table 4:
-
TABLE 4 Exp 2a Exp 2b Exp 2c TPA formation No Yes Yes Decrease in TPAI 4 43 91 content (%) - These results demonstrate that high hydrolysis catalyst concentration (which could result from adding too much hydrolysis catalyst after degradation of hydrolysis catalyst has been detected) can have a detrimental effect on the stability of the carboxylation catalyst. In a preferred embodiment of the present invention, when an additional charge of the hydrolysis catalyst is added, the amount of additional catalyst is preferably such that the total concentration of hydrolysis catalyst will not be above an upper limit. This avoids the degradation of carboxylation catalyst illustrated by this experiment.
- In this experiment the effect of the amount of a commonly used basic hydrolysis catalyst (KOH) on the stability of a commonly used carboxylation catalyst, tetra-n-butylphosphoniumbromide, (TBPB) is evaluated under conditions representative for distillation column (7) and with a composition representative for the process stream of line (6) and the contents of column (7).
- Table 5 shows the conditions for experiments 3a-3c:
-
TABLE 5 Exp 3a Exp 3b Exp 3c Water (g) 11 11 11 Monoethylene glycol (g) 47 47 47 TBPB (g) 22.5 23.3 24.7 TBPB (mol/l) 0.80 0.80 0.80 KOH (g) 1.40 3.37 7.14 KOH (mol/l) 0.30 0.70 1.40 Temperature (° C.) 165 165 165 N2 pressure (barg) 12.5 12.5 12.5 Time (h) 193 193 193 - After 193 h the resulting mixture was analyzed by 31P NMR; TBPB catalyst degradation is visible by a decline in TBPB content and the formation of TBPO (tri-n-butylphosphine oxide), which is a TBPB degradation product. The results are shown in Table 6:
-
TABLE 6 Exp 2a Exp 2b Exp 2c TBPO formation Yes Yes Yes Decrease in TBPB 0.8 2.3 18.1 content (mol %) - Again, these results demonstrate that high hydrolysis catalyst concentration (which could result from adding too much hydrolysis catalyst after degradation of hydrolysis catalyst has been detected) can have a detrimental effect on the stability of the carboxylation catalyst. In a preferred embodiment of the present invention, when an additional charge of the hydrolysis catalyst is added, the amount of additional catalyst is preferably such that the total concentration of hydrolysis catalyst will not be above an upper limit. This avoids the degradation of carboxylation catalyst illustrated by this experiment.
Claims (13)
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US9260366B2 (en) * | 2011-01-24 | 2016-02-16 | Shell Oil Company | Process for the production of ethylene oxide |
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CN105272823B (en) * | 2014-07-03 | 2017-04-19 | 中国石油化工股份有限公司 | Method for preparing C2-10 alkanediol |
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KR20130122623A (en) * | 2010-10-19 | 2013-11-07 | 쉘 인터내셔날 리써취 마트샤피지 비.브이. | Process for the production of alkylene glycol |
KR101881614B1 (en) * | 2010-10-19 | 2018-07-24 | 쉘 인터내셔날 리써취 마트샤피지 비.브이. | Process for the production of alkylene glycol |
US9260366B2 (en) * | 2011-01-24 | 2016-02-16 | Shell Oil Company | Process for the production of ethylene oxide |
Also Published As
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CA2720213A1 (en) | 2009-10-15 |
EP2294042A1 (en) | 2011-03-16 |
CN102036940A (en) | 2011-04-27 |
WO2009124988A1 (en) | 2009-10-15 |
BRPI0911055B1 (en) | 2017-10-24 |
US8110712B2 (en) | 2012-02-07 |
RU2010145531A (en) | 2012-05-20 |
TW200948762A (en) | 2009-12-01 |
CN102036940B (en) | 2013-11-13 |
TWI487691B (en) | 2015-06-11 |
RU2490247C2 (en) | 2013-08-20 |
BRPI0911055A2 (en) | 2015-12-29 |
JP2011516531A (en) | 2011-05-26 |
EP2294042B1 (en) | 2018-08-08 |
KR20100135263A (en) | 2010-12-24 |
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